Patient Acceptable Symptom State Thresholds for the Knee Society Score, Oxford Knee Score, and 36-Item Short Form Survey Ten Years Following Unicompartmental Knee Arthroplasty

BACKGROUND

The patient acceptable symptom state (PASS) refers to a cutoff value on any patient-reported outcome measures (PROMs) scale, beyond which patients consider themselves as having achieved an acceptable outcome. This study aimed to identify PASS thresholds for knee-specific and generic PROMs at 10 years post-unicompartmental knee arthroplasty (UKA).

METHODS

There were 269 patients who underwent UKA for medial osteoarthritis from 2004 to 2007 at a single institution and were surveyed preoperatively and 10 years postoperatively using the Knee Society Function Score (KSFS), Knee Society Knee Score (KSKS), Oxford Knee Score (OKS), 36-Item Short Form Survey (SF-36) Mental Component Score (MCS), and SF-36 Physical Component Score (PCS). Treatment outcomes and expectations were assessed using an anchor question, and PASS attainment was determined using the Youden index on a receiver operating characteristic (ROC) curve. Also, a similar study that identified 2-year long-term PROM PASS thresholds for UKA was referenced and compared.

RESULTS

Overall, 91.1% reported acceptable outcomes. The area under the curve for ROCs of KSKS, OKS, and PCS were 0.80, 0.75, and 0.71, respectively. The area under the curve for ROCs of KSFS and MCS were both 0.64. The PASS thresholds were 67.5 for KSFS, 70.5 for KSKS, 39.5 for OKS, 44.6 for PCS, and 43.8 for MCS. Patients who achieved a PASS were at least 3 times more likely to have satisfactory outcomes.

CONCLUSIONS

To our knowledge, this is the first study that identified 10-year long-term PROM PASS thresholds for UKA. Accounting for our finding that a decade-long follow-up yielded lower PASS thresholds, time-specific UKA PROM PASS thresholds should be considered.

LEVEL OF EVIDENCE

III.

Clinical Frailty Scale is a better predictor for adverse post-operative complications and functional outcomes than Modified Frailty Index and Charlson Comorbidity Index after total knee arthroplasty

PURPOSE

Studies have demonstrated correlations between frailty and comorbidity scores with adverse outcomes in total knee replacement (TKR). However, there is a lack of consensus on the most suitable pre-operative assessment tool. This study aims to compare Clinical Frailty Scale (CFS), Modified Frailty Index (MFI), and Charlson Comorbidity Index (CCI) in predicting adverse post-operative complications and functional outcomes following a unilateral TKR.

METHODS

In total, 811 unilateral TKR patients from a tertiary hospital were identified. Pre-operative variables were age, gender, body mass index (BMI), American Society of Anesthesiologists (ASA) class, CFS, MFI, and CCI. Binary logistic regression analysis was performed to ascertain odd ratios of pre-operative variables on adverse post-operative complications (length of stay < LOS >, complications, ICU/HD admission, discharge location, 30-day readmission, 2-year reoperation). Multiple linear regression analyses were used to estimate the standardized effects of pre-operative variables on the Knee Society Functional Score (KSFS), Knee Society Knee Score (KSKS), Oxford Knee Score (OKS), and 36-Item Short Form Survey (SF-36).

RESULTS

CFS is a strong predictor for LOS (OR 1.876, p < 0.001), complications (OR 1.83-4.97, p < 0.05), discharge location (OR 1.84, p < 0.001), and 2-year reoperation rate (OR 1.98, p < .001). ASA and MFI were predictors for ICU/HD admission (OR:4.04, p = 0.002; OR 1.58, p = 0.022, respectively). None of the scores was predictive for 30-day readmission. A higher CFS was associated with a worse outcome for 6-month KSS, 2-year KSS, 6-month OKS, 2-year OKS, and 6-month SF-36.

CONCLUSION

CFS is a superior predictor for post-operative complications and functional outcomes than MFI and CCI in unilateral TKR patients. This suggests the importance of assessing pre-operative functional status when planning for TKR.

LEVEL OF EVIDENCE

Diagnostic, II.

Does obesity lead to lower rates of clinically meaningful improvement or satisfaction after total hip arthroplasty? A propensity score-matched study

BACKGROUND

Current literature lacks consensus regarding the impact of obesity on clinical outcomes of total hip arthroplasty (THA). The variability of results may reflect the lack of minimal clinically important difference (MCID) analysis, which helps to standardise the interpretation of patient-reported outcome measures (PROMs). We compared the PROMs, patient satisfaction and survivorship between obese and non-obese patients after THA.

METHODS

Prospectively collected registry data of 192 obese patients and 192 propensity score-matched controls who underwent primary THA at a single institution were reviewed. Clinical outcomes and satisfaction rates were assessed at 6 months and 2 years. Reoperations for surgical complications and revision rates were analysed.

RESULTS

Obese patients had a significantly poorer Oxford Hip Score (OHS) at 6 months and WOMAC-Function at 2 years. However, there was no difference in overall WOMAC, WOMAC-Pain, WOMAC-stiffness, SF-36 mental and physical component summary (PCS). A similar proportion of patients in each group achieved the MCID for OHS, WOMAC and SF-36 PCS. At 2 years, 90.3% of obese patients and 91.7% of controls were satisfied (p = 0.755). At a mean follow-up of 9 years, there were 5 reoperations (2.6%) for surgical complications in the obese group and 1 (0.5%) in the control group; whereas 12 revisions (6.3%) were recorded in the obese group and 3 (1.6%) in the control group (p = 0.021).

CONCLUSIONS

Despite a higher revision rate, obese patients undergoing THA may experience a similar level of clinical meaningful improvement and satisfaction as their non-obese counterparts. This study provides valuable prognostic information for obese patients and guides preoperative counselling.

Bone-on-Bone Contact on Radiograph is not a Prerequisite for Successful Outcome in Fixed-Bearing Medial Unicompartmental Knee Arthroplasty-A 10-Year Follow-Up Study

INTRODUCTION

 Patients without bone-on-bone osteoarthritis are excluded from mobile-bearing unicompartmental knee arthroplasty due to higher revision rates and poorer outcomes. However, we do not know if the same indication applies to fixed-bearing unicompartmental knee arthroplasty implants. Our study aims to compare functional outcomes and revision rates in patients with and without bone-on-bone arthritis undergoing fixed-bearing medial unicompartmental knee arthroplasty.

MATERIALS AND METHODS

 We reviewed 153 fixed-bearing medial unicompartmental knee arthroplasties in a single institution. Patients were divided into four groups based on joint space remaining measured on preoperative radiographs. Group 1 included knees with bone-on-bone contact; group 2 included knees with less than 2 mm joint space; group 3 included knees with 2 to 4 mm joint space; group 4 included knees with more than 4 mm joint space. Patients were followed up for 10 years postoperatively and assessed using the Oxford Knee Score, the Functional Score and Knee Score from the Knee Society Clinical Rating Score, and the Short Form 36 Health Survey.

RESULTS

 There was no difference in terms of demographic data and preoperative scores. Postoperative Knee Society Functional Score was found to be lower in group 1 as compared with the other groups. There was no difference between the four groups of patients in terms of Knee Society Knee Score, Oxford Knee Score, and Physical Component Summary and Mental Component Summary Scores from the Short Form 36 Health Survey. There was no difference in terms of survivorship free from all-cause revision at a minimum of 10 years' follow-up.

CONCLUSION

 Symptomatic patients with varying degrees of arthritis on preoperative radiographs had comparable clinical outcomes. We conclude that symptomatic patients with clinical and radiographic evidence of medial compartment osteoarthritis of any grade can benefit from a fixed-bearing medial unicompartmental knee arthroplasty.

Preoperative Flexion Contracture Does Not Compromise the Outcomes and Survivorship of Medial Fixed Bearing Unicompartmental Knee Arthroplasty

BACKGROUND

Despite the expanding indications for unicompartmental knee arthroplasty (UKA), the classic indication that limits flexion contracture to <5° in fixed bearing UKA excludes most patients with arthritic knees and has not been challenged in modern literature. This study compared the clinical outcomes between patients with severe flexion contracture and controls undergoing UKA.

METHODS

Eighty seven medial fixed bearing UKAs performed in patients with severe (≥15°) flexion contracture were matched 1:1 with 87 controls without flexion or recurvatum deformity (-5°<extension<5°) using propensity scores to control for age, sex, BMI, Charlson comorbidity index, ASA class, and baseline patient-reported outcome measures (PROMs). Perioperative outcomes were recorded. Range of motion, Knee Society Score, Oxford Knee Score, SF-36, and patient satisfaction were assessed at 6 months and 2 years. Survivorship was recorded at mean 11.5 ± 3.2 years.

RESULTS

Preoperative knee extension in the control and contracture groups was 0.9° ± 1.9° and 18.0° ± 3.5° (P < .001), respectively, whereas flexion was 122.8° ± 27.9° and 120.6° ± 13.6° (P = .502). The contracture group had poorer Knee Society functional (P = .023) and SF-36 physical score (P = .010) at 6 months. However, there was no difference in PROMs at 2 years. A similar proportion achieved the minimal clinically important difference for each PROM and was satisfied with surgery. Range of motion remained poorer in the contracture group and a higher percentage had residual contractures (P < .001). Ten-year survivorship was 94% and 97% in the control and contracture groups, respectively (P = .145).

CONCLUSION

Although patients with severe flexion contractures had a poorer range of motion and postoperatively, these patients attained comparable PROMs, satisfaction rates, and mid-term survivorship after UKA.

LEVEL OF EVIDENCE

III, therapeutic study.

Preoperative Mental Health Influences Patient-Reported Outcome Measures and Satisfaction After Revision Total Knee Arthroplasty

BACKGROUND

A higher prevalence of mental health conditions has been reported in patients undergoing revision total knee arthroplasty (rTKA). This study investigated the effect of preoperative mental health on patient-reported outcome measures (PROMs) and satisfaction after rTKA.

METHODS

A total of 245 patients who underwent rTKA in 2004-2018 were identified from our institutional joint registry. The most common indications were aseptic loosening (n = 111), infection (n = 70), and instability (n = 35). 36-item Short-Form health survey (SF-36) mental component summary (MCS) was used to stratify the cohort into: Low-MCS (SF-36 MCS <50; n = 112) and control (SF-36 MCS ≥50; n = 133) groups. Knee Society score, Oxford knee score, SF-36 physical score, and a satisfaction questionnaire were used to compare the low-MCS and control at 6 months and 2 years.

RESULTS

All PROMs were poorer in the low-MCS group at 6 months and 2 years. However, both groups demonstrated a comparable improvement in each PROM and a similar proportion attained the minimal clinically important difference. Fewer patients in the low-MCS group were satisfied at 2 years (72.2% vs 84.5%, P = .045). Lower preoperative SF-36 MCS was independently associated with increased odds of dissatisfaction (OR 1.037, 95% CI 1.004-1.070, P = .027). Although the change in SF-36 MCS was greater in the low-MCS group, the final value remained lower at 2 years.

CONCLUSION

While patients with poor mental health had inferior PROMs preoperatively and postoperatively, a similar percentage experienced a clinically meaningful improvement at 2 years. Perioperative optimization of psychological factors should still be emphasized as these patients were at a higher risk of dissatisfaction after rTKA.

Patients With Parkinson's Disease Have Poorer Function and More Flexion Contractures After Total Knee Arthroplasty

BACKGROUND

Parkinson's disease (PD) may negatively influence the rehabilitative course after total knee arthroplasty (TKA). However, functional outcomes in this select group remain poorly defined. We compared complication, mortality and revision rates, as well as patient-reported outcomes, and satisfaction between patients with PD and controls after TKA.

METHODS

Patients with PD who underwent primary unilateral TKA were identified and matched 1:1 with a control group using propensity scores adjusting for age, sex, body mass index, Charlson Comorbidity Index, baseline range of motion, Knee Society Knee Score, Knee Society Function Score, Oxford Knee Score, and 36-item Short-Form Health Survey Mental and Physical Component Summary. Functional outcomes and patient satisfaction were assessed at 6 months and 2 years. Complications, survivorship, and all-cause mortality were analyzed.

RESULTS

In total, 114 patients were included. Majority of PD patients had Hoehn and Yahr stage 1 or 2 disease. Overall complication rate was 26.3% in the PD group and 10.5% in the control group (P = .030). There was no difference in transfusions, length of stay, and discharge to rehabilitation or readmissions. Patients with PD had more flexion contractures, poorer Knee Society Function Score and Oxford Knee Score at 2 years, and poorer 36-item Short-Form Health Survey Physical Component Summary at 6 months. 80.4% of patients with PD were satisfied compared with 85.5% of controls (P = .476). At follow-up of 8.5 ± 2.7 years, one TKA was revised in each group. All-cause mortality was higher in the PD group (15.8% vs 5.3%, P = .067).

CONCLUSION

Although patients with PD had relatively poorer knee function and quality of life, these patients still experienced significant functional gains compared with their preoperative status, and high satisfaction was achieved.

LEVEL OF EVIDENCE

III.

Early post-operative oxford knee score and knee society score predict patient satisfaction 2 years after total knee arthroplasty

BACKGROUND

There is poor correlation between functional outcomes and patient satisfaction following total knee arthroplasty (TKA). We asked if early post-operative scores at 6 months or the pre- to post-operative change in scores are predictive of patient satisfaction 2 years after TKA.

METHODS

We conducted a retrospective review of prospectively collected registry data of 4359 TKAs performed at a single institution. At 6 months and 2 years, the Knee Society Score (KSS), Oxford Knee Score (OKS), and Short-Form 36 scores were assessed. A satisfaction questionnaire was also completed. Logistic regression was used to generate receiver-operating characteristic (ROC) curves to assess the ability of each scoring system in predicting satisfaction at 2 years.

RESULTS

At 2 years, 91.1% of patients were satisfied. For the absolute post-operative OKS at 6 months, an AUC of 0.762 (95% CI 0.736-0.788) and a threshold of ≤ 21.5 points (or ≥ 38.5 points on the new scale) were obtained. For the KSS knee score, an AUC of 0.704 (95% CI 0.674-0.734) and a threshold of ≥ 80.5 points were identified. The OKS performed significantly better than the KSS knee score (p = 0.03) and the other post-operative scores (p < 0.001). When analysing the change in scores pre-operatively to 6 months, the AUC was < 0.7 for all scales.

CONCLUSIONS

Early post-operative scores, specifically the OKS and KSS knee score, can predict patient satisfaction at 2 years after TKA with good accuracy. The threshold values offer surgeons an additional tool to identify patients at risk of dissatisfaction at 2 years, enabling them to intervene earlier to ensure good patient satisfaction.

LEVEL OF EVIDENCE

III, retrospective cohort study.

Patient-reported Outcome Measures of Revision Total Hip Arthroplasty for Prosthetic Joint Infection is not Inferior to Aseptic Revision Total Hip Arthroplasty

Introduction:

This study aims to investigate whether patients undergoing two-stage revision total hip arthroplasty (THA) for prosthetic joint infection (PJI) and one-stage revision THA for aseptic reasons have similar clinical outcomes and patient satisfaction during their post-operative follow-up. We hypothesise that the two-stage revision THA for PJI is associated with poorer outcomes as compared to aseptic revision THA.

Materials and Methods:

We reviewed prospectively collected data in our tertiary hospital arthroplasty registry and identified patients who underwent revision THA between 2001 and 2014, with a minimum of two years follow-up. The study group (two-stage revision THA for PJI) consists of 23 patients and the control group (one-stage revision THA for aseptic reasons) consists of 231 patients. Patient demographics, Western Ontario and McMaster Universities Arthritis Index (WOMAC), Oxford Hip Score (OHS), Short Form-36 (SF-36) scores and patient reported satisfaction were evaluated. Student’s t-test was used to compare continuous variables between the two groups. Statistical significance was defined as p <0.05.

Results:

The pre-operative demographics and clinical scores were relatively similar between the two groups of patients. At two years, patients who underwent revision THA for PJI reported a better WOMAC Pain Score and OHS as compared to aseptic revision THA. A similar proportion of patients were satisfied with their results of surgery in both groups (p=0.093).

Conclusions:

Although patients who underwent revision THA for PJI had poorer pre-operative functional scores (WOMAC function and SF-36 PF), at two years follow-up, these two groups of patients have comparable post-operative outcomes. Interestingly, patients who had revision THA for PJI reported a better clinical outcome in terms of OHS and WOMAC Pain score as compared to the aseptic group. We conclude that the revision THA for PJI is not inferior to aseptic revision THA in terms of patient satisfaction and clinical outcomes.

Unicompartmental knee arthroplasty in patients with Parkinson's disease

BACKGROUND

Parkinson's disease (PD) adversely affects physical function after joint replacement. The biomechanical advantages of unicompartmental knee arthroplasty (UKA) may be particularly beneficial for these patients who suffer from gait and kinetic abnormalities. We aimed to describe the functional outcomes, complications and survivorship after UKA in patients with PD.

METHODS

Ten patients (11 knees) undergoing primary fixed-bearing UKA for medial osteoarthritis were studied. Knee Society Knee (KSKS) and Function Scores (KSFS), as well as the Short-Form-36 (SF-36) Mental (MCS) and Physical Component Scores (PCS) were assessed preoperatively, at six months and at two years postoperatively. Complications, survivorship and all-cause mortality were analyzed.

RESULTS

No perioperative complications occurred. Length of stay was 5 ± 2 days and no patients were discharged to rehabilitation or readmitted. Nine of 11 knees had a flexion contracture preoperatively and this remained unchanged at two years. KSKS and SF-36 PCS improved significantly. However, there was no improvement in KSFS or SF-36 MCS. All patients achieved minimal clinically important difference for KSKS, six of 11 for KSFS and nine of 11 for SF-36 PCS. At mean 10 ± 5 years, there was one revision for progression of osteoarthritis. Seven of 10 patients progressed in Hoehn and Yahr stage and only three were able to ambulate independently at last follow-up.

CONCLUSIONS

Patients suffering from osteoarthritis and PD can experience a substantial improvement in knee pain with low morbidity after UKA. However, the improved kinematics of UKA did not translate to an improved range of motion or knee function postoperatively.

Ten-Year Results of Unicompartmental Knee Arthroplasty in Patients With Psychological Distress

BACKGROUND

Although the influence of psychological distress on the outcomes of total knee arthroplasty has been described extensively, its effect on unicompartmental knee arthroplasty (UKA) is poorly defined. Furthermore, most studies in arthroplasty literature had short follow-ups of ≤1 year. We investigated the influence of psychological distress on long-term patient-reported outcomes and analyzed the change in mental health after UKA in a cohort with minimum 10 years of follow-up.

METHODS

Prospectively collected data of 269 patients undergoing UKA in 2004-2007 were reviewed. Patients were stratified into those with psychological distress (36-item Short-Form health survey [SF-36] Mental Component Summary [MCS] <50, n = 111) and those without (SF-36 MCS ≥50, n = 158). Clinical outcomes were obtained preoperatively, at 2 years, and 10 years. Multiple regression was used to control for age, gender, body mass index, Charlson Comorbidity Index, American Society of Anesthesiologists class, and baseline scores. The rate of expectation fulfillment and satisfaction was compared.

RESULTS

Psychologically distressed patients had poorer Knee Society Knee Score, Function Score, Oxford Knee Score, and SF-36 Physical Component Summary preoperatively, at 2 years, and 10 years. However, an equal proportion in each group attained the minimal clinically important difference for each score. Distressed patients had a comparable rate of satisfaction (91% vs 95%, P = .136) but lower fulfillment of expectations (89% vs 95%, P = .048). The percentage of distressed patients declined from 41% to 35% at follow-up. The mean SF-36 MCS improved by 6.9 points.

CONCLUSION

Although psychologically distressed patients had relatively greater pain and poorer function preoperatively and up to 10 years after UKA, a similar proportion of them experienced a clinically meaningful improvement in patient-reported outcomes.

Are Oxford Hip Score and Western Ontario and McMaster Universities Osteoarthritis Index Useful Predictors of Clinical Meaningful Improvement and Satisfaction After Total Hip Arthroplasty?

BACKGROUND

Up to 15% of patients express dissatisfaction after total hip arthroplasty (THA). Preoperative patient-report outcome measures (PROMs) scores can potentially mitigate this by predicting postoperative satisfaction, identifying patients that will benefit most from surgery. The aim of this study was to (1) calculate the minimal clinically important difference (MCID) thresholds for Oxford Hip Score (OHS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and the Short Form-36 (SF-36) mental component summary (MCS) and physical component summary (PCS) scores and (2) identify the threshold values of these PROMs that could be used to predict patient satisfaction and expectation fulfilment.

METHODS

Prospectively collected registry data of 1334 primary THA patients who returned for 2-year follow-up from 1998 to 2016 were reviewed. All patients were assessed preoperatively and postoperatively at 2 years using the OHS, WOMAC, and SF-36 PCS/MCS scores. The MCID for each PROMs was calculated, and the proportion of patients that attained MCID was recorded. The relationship between satisfaction, expectation fulfilment, and MCID attainment was analyzed using Spearman rank correlation. Optimal threshold scores for each PROM that predicted MCID attainment and satisfaction/expectation fulfilment at 2 years were calculated using receiver operating curve analysis.

RESULTS

The calculated MCID for OHS, WOMAC, SF-36 PCS, and SF-36 MCS were 5.2, 10.8, 6.7, and 6.2, respectively. A threshold value of 24.5 for the preoperative OHS was predictive of achieving WOMAC MCID at 2 years after THA (area under the curve 0.80, P < .001). 93.1% of patients were satisfied, and 95.5% had expectations fulfilled at 2 years. None of the PROMs were able to predict satisfaction.

CONCLUSION

OHS and WOMAC scores can be used to determine clinical meaningful improvement but are limited in their ability to predict patient satisfaction after THA.

Do Patients With Psychological Distress Have Poorer Patient-Reported Outcomes After Total Hip Arthroplasty?

BACKGROUND

Patients with psychological distress are likely to have poorer short-term functional outcomes after total knee arthroplasty. However, the influence of psychological distress on the outcomes of total hip arthroplasty (THA) is relatively understudied. Previous studies also had short follow-ups of 1 year or less. We examined the influence of psychological distress on patient-reported outcomes and satisfaction, and analyzed the change in mental health after THA at a minimum of 2 years.

METHODS

Prospectively collected data of 1384 patients undergoing primary THA in 2001-2015 were reviewed. Patients were assessed using the Oxford Hip Score, Western Ontario and McMaster Universities Osteoarthritis Index, and 36-item Short-Form health survey Physical Component Summary and Mental Component Score (MCS). Patients were stratified into those with psychological distress (MCS < 50, n = 720) and those without (MCS ≥ 50, n = 664). Multiple regression analysis was used to control for age, gender, body mass index, and baseline scores. The rate of satisfaction and expectation fulfillment was also analyzed.

RESULTS

Distressed patients had a poorer Physical Component Summary at 6 months. However, there was no difference in patient-reported outcomes at 2 years. A higher proportion of distressed patients attained the minimal clinically important difference for Oxford Hip Score and Western Ontario and McMaster Universities Osteoarthritis Index, while 92.2% of distressed patients and 92.9% of nondistressed patients were satisfied at 2 years (P = .724). There was no difference in MCS after 6 months. The percentage of distressed patients also declined from 41.8% to 27.3%.

CONCLUSION

Patients with psychological distress achieved a comparable level of function, quality of life, and satisfaction 2 years after THA. Undergoing THA may also lead to mental health improvement in a subgroup of distressed patients.

Should patients aged 75 years or older undergo medial unicompartmental knee arthroplasty? A propensity score-matched study

INTRODUCTION

With increasing life expectancies worldwide, more elderly patients with isolated medial compartment osteoarthritis may become suitable UKA candidates. However, there is a paucity of literature comparing outcomes between older patients (≥ 75 years) and younger patients undergoing UKA. The aim of this study was to determine if there were differences in functional and HRQoL measures between older patients (≥ 75 years) and younger controls (< 75 years) undergoing primary UKA.

MATERIALS AND METHODS

Prospectively collected registry data of 1041 patients who underwent primary, cemented, fixed-bearing medial UKA at a single institution from 2002-2013 were reviewed. Propensity scores generated using logistic regression was used to match older patients (≥ 75 years, n = 94) to controls (< 75 years, n = 188) in a 1:2 ratio. Knee Society Scores, Oxford Knee Score, Short Form-36, satisfaction/expectation scores, proportion of patients attaining OKS/SF-36 PCS MCID and survivorship were analysed.

RESULTS

Patients ≥ 75 years had significantly lower KSFS (67.1 ± 17.9 vs 79.4 ± 18.2, p < 0.001) and SF-36 PCS (47.3 ± 10.1 vs 50.4 ± 9.1, p = 0.01) as compared to the control group. In addition, a significantly lower proportion of patients ≥ 75 years attained MCID for SF-36 PCS when compared to the controls (50.0% vs 63.8%, p = 0.04). Survival rates at mean 8.3 ± 3.0 years were 98.9% (95% CI, 96.7-100) in the older group versus 92.8% (95% CI, 86.8-98.8) in the younger group (p = 0.31).

CONCLUSIONS

Our findings highlight the need to counsel older patients regarding potentially reduced improvements in functional outcomes, despite advantages of lower revision. However, UKA in older patients continues to be a viable option for isolated medial compartment osteoarthritis LEVEL OF EVIDENCE: Level III Propensity score matched study.

Can Octogenarians Undergoing Total Knee Arthroplasty Experience Similar Functional Outcomes, Quality of Life, and Satisfaction Rates as Their Younger Counterparts? A Propensity Score Matched Analysis of 1188 Patients

BACKGROUND

Current literature lacks consensus regarding the impact of advanced age on the clinical outcomes of total knee arthroplasty (TKA). Moreover, there is paucity of literature on the subjective benefit reported by elderly patients. We compared the functional outcomes, quality of life, and satisfaction rates between octogenarians and age-appropriate controls undergoing primary TKA with a minimum follow-up of 2 years.

METHODS

Prospectively collected registry data of 594 patients aged ≥80 years (n = 594) and a propensity score matched cohort of 594 patients aged 65-74 years who underwent primary TKA at a single institution were reviewed. The range of motion, clinical outcome scores, and satisfaction rates were assessed at 6 months and 2 years. Revision rates were also recorded.

RESULTS

Octogenarians had a significantly lower Knee Society Function Score, Oxford Knee Score, and SF-36 Physical Component Summary at 6 months and 2 years (P < .05 for each). Furthermore, a lower proportion of octogenarians achieved the minimal clinically important difference for each score (P < .05 for each). Although the rates were similar at 6 months (P = .853), octogenarians were less satisfied at 2 years compared to age-appropriate controls (89.3% vs 93.3%, P = .042), and there was a trend toward poorer expectation fulfillment (88.4% vs 92.1%, P = .062).

CONCLUSION

Octogenarians undergoing TKA had a relatively lower rate of satisfaction and clinically meaningful improvement compared to younger controls. Nevertheless, elderly patients still experienced a successful outcome after surgery. The clinical trajectory outlined may help clinicians provide valuable prognostic information to elderly patients and guide preoperative counseling.

The long-term impact of preoperative psychological distress on functional outcomes, quality of life, and patient satisfaction after total knee arthroplasty

Aims

While patients with psychological distress have poorer short-term outcomes after total knee arthroplasty (TKA), their longer-term function is unknown. We aimed to 1) assess the influence of preoperative mental health status on long-term functional outcomes, quality of life, and patient satisfaction; and 2) analyze the change in mental health after TKA, in a cohort of patients with no history of mental health disorder, with a minimum of ten years’ follow-up.

Methods

Prospectively collected data of 122 patients undergoing primary unilateral TKA in 2006 were reviewed. Patients were assessed pre- and postoperatively at two and ten years using the Knee Society Knee Score (KSKS) and Function Score (KSFS); Oxford Knee Score (OKS); and the Mental (MCS) and Physical Component Summary (PCS) which were derived from the 36-Item Short-Form Health Survey questionnaire (SF-36). Patients were stratified into those with psychological distress (MCS < 50, n = 51) and those without (MCS ≥ 50, n = 71). Multiple regression was used to control for age, sex, BMI, Charlson Comorbidity Index (CCI), and baseline scores. The rate of expectation fulfilment and satisfaction was compared between patients with low and high MCS.

Results

There was no difference in the mean KSKS, KSFS, OKS, and SF-36 PCS at two years or ten years after TKA. Equal proportions of patients in each group attained the minimal clinically important difference for each score. Psychologically distressed patients had a comparable rate of satisfaction (91.8% (47/51) vs 97.1% (69/71); p = 0.193) and fulfilment of expectations (89.8% vs 97.1%; p = 0.094). The proportion of distressed patients declined from 41.8% preoperatively to 29.8% at final follow-up (p = 0.021), and their mean SF-36 MCS improved by 10.4 points (p < 0.001).

Conclusion

Patients with poor mental health undergoing TKA may experience long-term improvements in function and quality of life that are comparable to those experienced by their non-distressed counterparts. These patients also achieved a similar rate of satisfaction and expectation fulfilment. Undergoing TKA was associated with improvements in mental health in distressed patients, although this effect may be due to residual confounding. Cite this article: Bone Joint J 2020;102-B(7):845–851.

Modern TKA implants are equivalent to traditional TKA implants in functional and patellofemoral joint-related outcomes

PURPOSE

To compare patient-reported outcomes measures, health-related quality of life and satisfaction rates between a new Modern TKA system (M-TKA) and an existing Traditional TKA system (T-TKA).

METHODS

Prospectively collected registry data of 65 patients who underwent T-TKA and 65 patients who underwent M-TKA at a single institution from 2014 to 2015 was reviewed. The range of motion, Knee Society Knee Score (KSKS), Function Score (KSFS), Oxford Knee Score (OKS), SF-36, satisfaction and expectation fulfilment were compared at Pre-op, 6 months and 2 years. Patellofemoral joint-related OKS subscores (3, 5, 7, 12) were also compared between the groups. Minimal clinically important difference (MCID) in OKS/SF-36 were analysed for both groups. Propensity scores generated using logistic regression were used to adjust for confounding variables, thus allowing matching of T-TKA to M-TKA in a 1:1 ratio.

RESULTS

Both groups showed a significant improvement in all measured variables at 6 month and 2 years (p < 0.001) when compared to baseline. There was no significant difference in KSKS, KSFS, OKS, SF-36 and Patellofemoral joint-related OKS subscores (3, 5, 7, 12) between the two groups (n.s.). At 2 years, there were high satisfaction rates of 89.2% and 92.2% in the T-TKA and M-TKA groups, respectively (n.s.). Similarly, both groups demonstrated high expectation fulfilment rates of 84.6% and 90.6% for the T-TKA and M-TKA groups, respectively (n.s.).

CONCLUSION

Using an extensive battery of standardized patient-reported, health-related quality of life and MCID assessments, our study demonstrated no difference in clinical outcomes between M-TKA and T-TKA that would justify the use of the newer and costlier M-TKA. Longer follow-up is necessary to evaluate the possible advantages of this new implant design.

LEVEL OF EVIDENCE

Level III, Retrospective Study.

Acceptable Functional Outcomes and Patient Satisfaction Following Total Knee Arthroplasty in Asians with Severe Knee Stiffness: A Matched Analysis

Background

This study evaluated outcomes following total knee arthroplasty for severely stiff knees in Asians.

Methods

Registry data of patients undergoing primary total knee arthroplasty between 2004 and 2013 were collected and retrospectively reviewed. Sociodemographic and anthropometric data together with the Oxford Knee Score and the Knee Society Score (Knee Society Knee Score and the Knee Society Function Score) were collected both preoperatively and postoperatively for up to 2 years. Case subjects consisted of patients with a preoperative flexion range of ≤ 20°. Control subjects consisted of patients with a preoperative flexion range of > 90°. Patients were matched for age, sex, and all preoperative scores in a 2:1 fashion. Two-year outcomes and 5-year revision rates were then compared between cases and controls.

Results

There were 28 cases and 56 controls. Cases had a significantly lower body mass index than the controls (p = 0.003) and had a longer hospital stay (p < 0.0001). At 2 years, cases had a significantly lower flexion range (p < 0.001) and a lower Knee Society Function Score (p = 0.020) than the controls. Cases had a significantly greater improvement in the flexion range (p < 0.001) postoperatively than controls. The mean change in functional outcomes at 2 years was comparable between the two groups. Seventy-one percent of the cases and 88% of controls were satisfied. There was a significant difference in the 5-year revision rate (10% vs 0%, p = 0.013). More cases were discharged to a rehabilitation facility compared to controls (p = 0.011). There were no differences in inpatient complication rates.

Conclusions

Functional outcomes and patient satisfaction were acceptable following total knee arthroplasty in Asian patients with severe knee stiffness.

Patients With Poor Baseline Mental Health Undergoing Unicompartmental Knee Arthroplasty Have Poorer Outcomes

BACKGROUND

The relationship between mental health and outcomes of unicompartmental knee arthroplasty (UKA) remains unclear. Poor preoperative mental health may be caused by pain and functional limitations associated with knee arthritis. We aimed at (1) investigating the effect of preoperative mental health on early outcomes and (2) assessing whether mental health improves after UKA.

METHODS

Prospectively collected registry data of 1473 medial UKAs performed at a single institution in 2007-2014 were reviewed. Linear regression was used to determine improvement in mental health up to 2 years according to preoperative Short-Form 36 Mental Component Summary (MCS). Patients were stratified into low MCS (<50, n = 579) and high MCS (≥50, n = 894). The Knee Society Knee Score (KSKS), Function Score (KSFS), Oxford Knee Score (OKS), Short-Form 36, satisfaction, and expectation fulfilment were compared at 6 months and 2 years.

RESULTS

The mean preoperative MCS was 41.2 in low MCS group and 58.6 in high MCS group (P < .001). The high MCS group had higher KSKS, KSFS, OKS, and Physical Component Summary, and a greater proportion of patients were satisfied and had expectations fulfilled at 6 months and 2 years (P < .05). However, the low MCS group demonstrated greater improvement in KSKS, KSFS, and OKS (P < .05). Lower preoperative MCS score was predictive of greater improvement in MCS (coefficient = -0.662, R = -0.602, P < .001).

CONCLUSION

Patients with poor mental health benefit from greater improvements in their mental health and knee function after UKA, but also have a greater dissatisfaction.

The influence of obesity on functional outcome and quality of life after total knee arthroplasty: a ten-year follow-up study

Aims

This study investigated the influence of body mass index (BMI) on patients' function and quality of life ten years after total knee arthroplasty (TKA).

Patients and Methods

A total of 126 patients who underwent unilateral TKA in 2006 were prospectively included in this retrospective study. They were categorized into two groups based on BMI: < 30 kg/m² (control) and ≥ 30 kg/m² (obese). Functional outcome was assessed using the Knee Society Function Score (KSFS), Knee Society Knee Score (KSKS), and Oxford Knee Score (OKS). Quality of life was assessed using the Physical (PCS) and Mental Component Scores (MCS) of the 36-Item Short-Form Health Survey.

Results

Results Patients in the obese group underwent TKA at a younger age (mean, 63.0 years, sd 8.0) compared with the control group (mean, 65.6 years, sd 7.6; p = 0.03). Preoperatively, both groups had comparable functional and quality-of-life scores. Ten years postoperatively, the control group had significantly higher OKS and MCS compared with the obese group (OKS, mean 18 (sd 5) vs mean 22 (sd 10), p = 0.03; MCS, mean 56 (sd 10) vs mean 50 (sd 11), p = 0.01). After applying multiple linear regression with the various outcomes scores as dependent variables and age, gender, and Charlson Comorbidity Index as independent variables, there was a clear association between obesity and poorer outcome in KSFS, OKS, and MCS at ten years postoperatively (p < 0.01 in both KSFS and OKS, and p = 0.03 in MCS). Both groups had a high satisfaction rate (97.8% in the control group vs 87.9% in the obese group, p = 0.11) and fulfillment of expectations at ten years (98.9% in the control group vs 100% in the obese group, p = 0.32).

Conclusion

Although both obese and non-obese patients have significant improvements in function and quality of life postoperatively, obese patients tend to have smaller improvements in the OKS and MCS ten years postoperatively. It is important to counsel patients on the importance of weight management to achieve a more sustained outcome after TKA. Cite this article: Bone Joint J 2018;100-B:579-83.

Unicompartmental Knee Arthroplasty Achieves Greater Flexion With No Difference in Functional Outcome, Quality of Life, and Satisfaction vs Total Knee Arthroplasty in Patients Younger Than 55 Years. A Propensity Score-Matched Cohort Analysis

BACKGROUND

Improvements in surgical techniques, implant design, and adherence to indications have resulted in favorable outcomes after unicompartmental knee arthroplasty (UKA), particularly in an older population. However, no studies have compared the performance of contemporary UKA and total knee arthroplasty (TKA) in a young population.

METHODS

Prospectively collected registry data of 160 UKAs performed in 160 patients younger than 55 years were reviewed. Propensity scores generated using logistic regression were used to adjust for confounding variables of age, gender, body mass index, preoperative range of motion, Knee Society Score, Oxford Knee Score, and Short-Form 36, allowing matching of the TKA cohort to the UKA cohort in a 1:1 ratio using the nearest-neighbor method.

RESULTS

The UKA group had significantly greater flexion at 6 months and 2 years (P < .001). There was no significant difference in Knee Society Score, Oxford Knee Score, and Short-Form 36. At 2 years, 89.4% and 88.8% of the TKA and UKA groups were satisfied (P = 1.00) while 86.9% and 86.3% had their expectations fulfilled (P = 1.00). At a mean follow-up of 7 years, there were 2 revisions in each group (2.2%).

CONCLUSION

Although native knee biomechanics are preserved, younger patients do not seem to perceive this oft-cited benefit of UKA, as this did not translate into greater health-related quality of life or patient satisfaction compared to TKA. The theoretical advantages of UKA were not borne out by our findings, other than greater flexion up to 2 years postoperatively.

Predictors of Midterm Outcomes after Medial Unicompartmental Knee Arthroplasty in Asians

Background

This study was designed to evaluate predictors of good outcomes following medial unicompartmental knee arthroplasty (UKA) in Asian patients.

Methods

Registry data of patients who underwent primary unilateral medial UKA from 2006 to 2011 were collected. Outcomes studied were the Oxford Knee Score (OKS) and the Physical Component Score (PCS) of the Short Form 36 (SF-36) questionnaire. These outcome scores were collected prospectively, pre- and postoperatively up to 5 years. Good outcome was defined as an overall improvement in score greater than or equal to the minimal clinically important difference (MCID). The MCID for the OKS was 5 while the MCID for the PCS was 10. Regression analysis was used to identify predictors of good outcomes following medial UKA.

Results

Primary medial UKA was performed in 1,075 patients. Higher (poorer) preoperative OKS (odds ratio [OR], 1.27; p < 0.001), lower (poorer) preoperative PCS (OR, 1.08; p < 0.001), lower (poorer) preoperative Knee Society Knee Score (KSKS; OR, 1.02; p < 0.001) and higher (better) preoperative SF-36 Mental Component Score (MCS; OR, 1.02; p < 0.001) were significant predictors of good outcomes.

Conclusions

Patients with poorer OKS, PCS and KSKS and better SF-36 MCS preoperatively tended to achieve good outcomes by the MCID criterion at 5 years following the index surgery.

Patient-Reported Outcomes, Quality of Life, and Satisfaction Rates in Young Patients Aged 50 Years or Younger After Total Knee Arthroplasty

BACKGROUND

Recent studies have shown a discrepancy between traditional functional outcomes and patient satisfaction, with some reporting less than 85% satisfaction in older patients undergoing total knee arthroplasty (TKA). As native knee biomechanics are not completely replicated, the resulting functional limitations may cause dissatisfaction in higher-demand individuals. Few studies have recorded patient-reported outcomes, health-related quality of life scores, and patient satisfaction in a young population undergoing TKA.

METHODS

One hundred thirty-six primary TKAs were performed in 114 patients aged 50 years or younger (mean age, 47.0 years; range, 30-50 years) at a single institution. The main diagnoses were osteoarthritis (85%) and rheumatoid arthritis (10%).

RESULTS

The range of motion, Knee Society Score, Oxford Knee Score, and Physical and Mental Component Scores of Short Form-36 increased significantly (P < .001). At 2 years, 85.3% of patients had good/excellent knee scores, 71.3% had good/excellent function scores, 94.9% met the minimal clinically important difference for the Oxford Knee Score, and 84.6% met the minimal clinically important difference for the Physical Component Score. We found that 88.8% of patients were satisfied with their surgeries, whereas 86.8% had their expectations fulfilled. Survivorship using revision as an end point was 97.8% at a mean of 7 years (range, 3-16 years).

CONCLUSION

Patients aged 50 years or younger undergoing TKA can experience significant improvements in their quality of life, have their expectations met, and be satisfied with their surgeries, at rates similar to those of non-age-restricted populations. Surgeons should inform them of these benefits and the potential risk of revision surgery in the future, albeit increasingly shown to be low.

The influence of body mass index on functional outcome and quality of life after total knee arthroplasty

AIMS

This study investigated the influence of body mass index (BMI) on the post-operative fall in the level of haemoglobin (Hb), length of hospital stay (LOS), 30-day re-admission rate, functional outcome and quality of life, two years after total knee arthroplasty (TKA).

PATIENTS AND METHODS

A total of 7733 patients who underwent unilateral primary TKA between 2001 and 2010 were included. The mean age was 67 years (30 to 90). There were 1421 males and 6312 females. The patients were categorised into three groups: BMI < 25.0 kg/m(2) (normal); BMI between 25.0 and 39.9 kg/m(2) (obese); and BMI ≥ 40.0 kg/m(2) (morbidly obese).

RESULTS

Compared with the normal and obese groups, the mean LOS was longer by one day (95% confidence interval (CI) 0 to 2) in the morbidly obese group (p = 0.003 and p = 0.001 respectively). The 30-day re-admisison rate was also higher in the morbidly obese group compared to the obese group (OR 2.323, 95% CI 1.101 to 4.900, p = 0.024); and showed a higher trend compared to the normal group (OR 1.850, 95% CI 0.893 to 3.831, p = 0.100). However, the morbidly obese group had a smaller drop in post-operative Hb level by a mean of 0.5 g/dl (0.3 to 0.6) and 0.3 g/dl (0.1 to 0.5), when compared with the normal and obese groups respectively (both p < 0.001). Furthermore, the mean improvement in Oxford Knee Score (OKS) and Knee Society Knee Score (KSKS) at two years follow-up was three points (two to four) and five points (two to seven) more in the morbidly obese group than in the normal group (both p < 0.001). The mean improvement in Knee Society Function Score, and Physical and Mental Component Scores of Short Form-36 were comparable between the three BMI groups (p = 0.736, p = 0.739 and p = 0.731 respectively). The ten-year rate of survival was 98.8% (98.0 to 99.3), 98.9% (98.5 to 99.2) and 98.0% (95.8 to 100), for the normal, obese and morbidly obese groups, respectively (p = 0.703).

CONCLUSION

Although morbidly obese patients have a longer LOS and higher 30-day re-admission rate after TKA, they have a smaller drop in post-operative Hb level and larger improvement in OKS and KSKS at two years follow-up. The ten-year rate of survival of TKA was also comparable with those with a normal BMI.

TAKE HOME MESSAGE

Morbidly obese patients should not be excluded from the benefits of TKA. Cite this article: Bone Joint J 2016;98-B:780-5.

Clinical outcomes of computer-assisted total knee arthroplasty using pinless navigation

This study aims to evaluate the 2-year post-operative clinical outcomes of patients undergoing total knee arthroplasty (TKA) with computer-assisted surgery (CAS) using the pinless BrainLAB^® VectorVision^® Knee 2.5 Navigation System versus standard CAS. A retrospective case-control study of 200 patients who underwent TKA with CAS from 2008 to 2012 was conducted. Patients in the pinless arm underwent a shorter duration of surgery compared to the standard CAS arm with 72 ± 13 min and 83 ± 11 min, respectively ( p < 0.001), with improvement in Oxford Knee Score from 34 ± 8 to 18 ± 5 and 34 ± 9 to 18 ± 5, respectively, without statistically significant differences in clinical outcomes at 2 years.

Early Outcomes of Unicompartmental Knee Arthroplasty in Patients With Preoperative Genu Recurvatum of Non-neurological Origin

BACKGROUND

This study aims to evaluate outcomes of unicompartmental knee arthroplasty (UKA) in patients with preoperative genu recurvatum.

METHODS

From patients who underwent UKA at a tertiary hospital between 2005 and 2012, the study selected 30 patients with genu recurvatum (group A) compared with a matching cohort of 60 without genu recurvatum (group B). Group A was also compared with a matched cohort of 60 patients with genu recurvatum who underwent total knee arthroplasty (group C). Functional outcomes data were prospectively collected at 6-month and 2-year follow-up.

RESULTS

Two years after UKA, group A had poorer Oxford Knee Score of 22 ± 8 compared with group B at 16 ± 3 (P < .001), and the trend is reflected in the Knee Society Score (71 ± 17 vs 87 ± 17, P < .001) and the 36 Item Short Form Health Survey Physical Component Score (47 ± 10 vs 52 ± 6, P = .014). After 2 years, group C had superior Oxford Knee Score (16 ± 2, P < .001), Knee Society Score (82 ± 14, P = .003), and 36 Item Short Form Health Survey Physical Component Score (53 ± 6, P = .005). The hyperextension angle in group A decreased from 6° ± 2° to 2° ± 4° after 2 years with an improvement of 4° ± 4° (P < .001). The hyperextension angle in group C decreased from 7° ± 2° to 1° ± 3° after 2 years with an improvement of 6° ± 3° (P < .001) with a significant difference (P = .002) in hyperextension angle correction between group A and C.

CONCLUSION

Preoperative recurvatum is a predictor of poorer outcome after UKA, and this patient population benefits from better 2-year functional outcomes after total knee arthroplasty.

Age and Preoperative Knee Society Score Are Significant Predictors of Outcomes Among Asians Following Total Knee Arthroplasty

BACKGROUND

The ability to predict patients' functional outcomes will add value to preoperative counseling. The purpose of this study was to evaluate predictors of good outcomes following total knee arthroplasty (TKA) among Asian patients.

METHODS

Registry data from 2006 to 2010 were extracted. The Oxford Knee Score (OKS) and the Short Form (SF)-36 physical component summary (PCS) were used to evaluate outcomes. A "good outcome" was defined as an improvement in scores of greater than or equal to the minimal clinically important difference (MCID) in the primary analysis. The MCID for the OKS was 5, and the MCID for the PCS was 10. For the sensitivity analyses, a "good outcome" was defined as an OKS of <30 and a PCS score of >50. Clinical variables were used to develop a multiple logistic regression model for a good outcome following total knee arthroplasty at 5 years.

RESULTS

Follow-up data were available for 3,062 patients who underwent primary TKA (mean age of 66.4 years; 79.5% female). Eighty-five percent had a good outcome on the basis of the OKS and 83%, on the basis of the SF-36 PCS. Age and preoperative Knee Society score (KSS) were found to be significant predictors. When outcomes were assessed by the MCID, lesser age and lower (worse) preoperative KSS predicted a good outcome at 5 years. When outcomes were assessed by absolute criteria (postoperative scores measured against OKS and PCS thresholds), a higher (better) preoperative KSS predicted a good outcome at 5 years. Body mass index, preoperative flexion range, SF-36 mental component summary (MCS) score, mechanical alignment, sex, education level, ethnicity, operative side, number of comorbidities, type of anesthesia, and type of implant were found not to be significant predictors.

CONCLUSIONS

The majority of Asian patients with osteoarthritis had good outcomes according to the MCID criterion and benefitted from primary TKA. On the basis of our findings, we believe that older patients with a lower (worse) preoperative KSS can be informed that they have a high likelihood of improvement but a lower likelihood of achieving as good a functional outcome as those with better scores.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Obesity and the absence of trochlear dysplasia increase the risk of revision in patellofemoral arthroplasty

PURPOSE

Proper indications and patient selection are of paramount importance in patellofemoral arthroplasty (PFA). Although factors predicting outcomes in total knee arthroplasty (TKA) have been studied, there are no such studies for modern PFA. This retrospective study reports the midterm clinical and radiological outcomes and survivorship of PFA, investigating the risk factors associated with poorer outcomes and higher revision rates.

METHODS

Fifty-one patients (51 knees) with isolated patellofemoral arthritis underwent PFA with a second-generation implant. The mean follow-up duration was 4.1 years (range, 2.2 to 6.1). The cohort was stratified into obese (body mass index (BMI)≥30 kg/m(2), n=16), overweight (BMI 25 to 29.9 kg/m(2), n=20) and control (BMI 18.5 to 24.9 kg/m(2), n=15) groups. The same cohort was stratified based on the presence (n=11) or absence (n=40) of trochlear dysplasia (TD).

RESULTS

The mean Knee Society objective and function scores, the Melbourne Knee score and the Physical Component Score of Short Form 36 improved significantly. Obesity was associated with no significant improvement in the Melbourne Knee score and the Knee Society function score (p>0.05), a higher incidence of radiographic outliers and lower patient satisfaction. There was no significant difference in outcomes between the TD and non-TD groups at two years (p>0.05), with a survivorship of 92.2%. Three revisions for progression of tibiofemoral osteoarthritis were noted in the non-TD and obese or overweight groups.

CONCLUSIONS

Patients with obesity and the absence of TD are at a potentially higher risk of revision surgery to TKA, and they should be counselled that PFA may represent a 'bridging' procedure.

LEVEL OF EVIDENCE

III.

Reducing allograft contamination and disease transmission: intraosseous temperatures of femoral head allografts during autoclaving

INTRODUCTION

The Singapore General Hospital Bone Bank, which exclusively stores femoral head allografts, relies on flash sterilisation to prevent allograft-related disease transmission and wound infection. However, intraosseous temperatures during autoclaving may be lower than required to eliminate human immunodeficiency virus, and hepatitis B and C viruses. The aim of this study is to determine the intraosseous temperatures of femoral head allografts during autoclaving and to assess the adequacy of autoclaving in preventing disease transmission.

METHODS

Six femoral heads were acquired from patients who underwent hip arthroplasty. The specimens were divided into two groups. The first group underwent flash sterilisation with a sterilisation time of 4 min, while a longer sterilisation time of 22 min was used for the second group.

RESULTS

The highest core temperature in the first group was 130°C, while the core temperatures in the second group plateaued at 133°C for all allografts. In the first group, only smaller allografts maintained temperatures sufficient for the inactivation of the clinically relevant viral pathogens. In contrast, all allografts in the second group were terminally sterilised.

CONCLUSION

There is an inverse correlation between the size of allografts and intraosseous temperatures achieved during autoclaving. Therefore, we recommend dividing large allografts into smaller pieces, in order to achieve intraosseous temperatures adequate for the elimination of transmissible pathogens during flash sterilisation. Allografts should not be terminally sterilised, as the resulting allografts will become unusable. Despite modern processing techniques, stringent donor selection remains vital in the effort to prevent allograft-related infections. Autoclaving is an economical and efficacious method of preventing allograft-related disease transmission.

Recovery in knee range of motion reaches a plateau by 12 months after total knee arthroplasty

PURPOSE

The primary aim of this study was to identify the time point at which improvements in knee range of motion reach a plateau, if any. The secondary aim of this study was to investigate the correlation between the improvements in knee range of motion and patient-reported outcomes [Oxford knee score (OKS) and SF-36]. The hypothesis is that there is a time point at which the recovery in the knee range of motion after total knee arthroplasty (TKA) plateaus.

METHOD

A prospective study of 145 patients who underwent TKA was conducted. All TKAs were performed by the same surgeon. OKS and SF-36 scores were measured preoperatively and at 6, 12, and 24 months. Range of motion was measured preoperatively and at 1, 3, 6, 12, and 24 months postoperatively.

RESULTS

This study shows that for surgeon/therapist reported range of motion, a plateau in recovery was reached at 12 months after TKA. It was also found that range of extension is significantly correlated with OKS, whereas range of flexion was not significantly correlated with OKS.

CONCLUSIONS

Knowledge of when patients fully recover after TKA will allow appropriate counseling of patients during preoperative consultation. Also, this knowledge will enable surgeons/therapists to better monitor the rehabilitation progress of TKA patients, and make adjustments to the rehabilitation protocol. In addition, our study shows that objective surgeon-/therapist-measured outcome (range of motion) has a significant correlation with subjective patient-reported outcomes (OKS). Hence, both outcome measures should be employed in the postoperative monitoring of patient progress.

LEVEL OF EVIDENCE

Prospective case series, Level IV.

Association of surgeon factors with outcome scores after total knee arthroplasty

PURPOSE

To identify preoperative factors (including surgeon factors) associated with outcome scores after total knee arthroplasty (TKA).

METHODS

Medical records of 2848 patients (3458 knees) who underwent primary TKA by 27 orthopaedic specialists were retrieved. Three specialty knee surgeons who had one-year fellowship in TKA performed 1930 TKAs, and 24 general orthopaedic surgeons performed 1528 TKAs. Four of them (including all 3 specialty knee surgeons) were ultrahigh- volume (≥ 100 TKAs a year), and 21 of them were senior consultants (≥ 5 years post residency). At 2 years, 2922 (85%) of knees had complete followup data. Oxford Knee Score, Knee Society knee and function scores, and SF-36 quality-of-life score were assessed by independent physiotherapists before and after surgery. Outcomes were compared in terms of dichotomised specialty, seniority, and surgical volume of surgeons.

RESULTS

Comparing ultra-high-volume (≥ 100 TKAs per year) specialty knee surgeons with general orthopaedic surgeons, the former achieved better outcomes in terms of the Oxford Knee Score at 6 months, Knee Society knee and function scores at 2 years, and SF-36 scores at 6 months and 2 years. Comparing lower-volume (<100 TKAs per year) specialty knee surgeons with general orthopaedic surgeons, the former still achieved better outcome and quality-of-life scores, except for SF-36 Mental Component Score at 2 years.

CONCLUSION

Specialty training and clinical research in TKA improved outcome and quality-of-life scores.

Associations of self-report physical function with knee strength and knee range-of-motion in total knee arthroplasty possible nonlinear and threshold effects

This study aims to examine, in patients before and following a total knee arthroplasty (TKA), whether knee extensor strength and knee flexion/extension range-of-motion (ROM) were nonlinearly associated with physical function. Data from 501 patients with TKA were analyzed. Knee extensor strength was assessed preoperatively and 6 months postoperatively. Knee ROM and Short Form-36 (SF-36) physical function data were collected from each patient preoperatively, and at 6 and 24 months postoperatively. Knee strength was measured by handheld dynamometry and knee ROM by goniometry. Restricted cubic spline regression was used to examine possible nonlinear associations. At all assessment points, the associations between knee measures and function were not always linear. Some of the associations revealed distinct threshold points. These findings have potential clinical and research implications.

Joint line changes and outcomes in constrained versus unconstrained total knee arthroplasty for the type II valgus knee

PURPOSE

The objective of this study was to compare the outcome of constrained and unconstrained primary total knee arthroplasty (TKA) in the management of the valgus deformity.

METHODS

This is a retrospective review of patients with type II valgus knee who underwent primary TKA from 1999 to 2011. There were fifty patients in Group 1 who underwent varus-valgus constrained TKA. They were matched with another fifty patients in Group 2 who underwent unconstrained TKA.

RESULTS

The mean joint line shift was significantly higher in Group 1 (+8 mm, SD 6 mm) than in Group 2 (+2 mm, SD 3 mm) (p = 0.03). At 2 years, there was no difference in anterior-posterior stability and mediolateral stability according to the Knee Society Score, and patients in Group 2 reported significantly better mean function score of 66.2 (SD 9.3) (mean 48, SD 7.1 in Group 1) (p = 0.002). Two patients (6 %) in Group 1 underwent revision surgery--one for a broken central peg and the other for aseptic loosening. Three patients (2 %) in Group 2 underwent revision surgery--two for global instability and one for poly wear. The estimated survivorship time was 8.3 years for constrained TKA and 12.0 for unconstrained TKA.

CONCLUSION

Constrained TKA was associated with more significant joint line changes for the management of valgus arthritic knee, when compared with unconstrained TKA.

LEVEL OF EVIDENCE

Retrospective study, Level III.

Comparison of the responsiveness of the SF-36, the Oxford Knee Score, and the Knee Society Clinical Rating System in patients undergoing total knee replacement

OBJECTIVES

To compare the responsiveness of the Knee Society (KS) Clinical Rating System, the general health status measure Short Form 36 (SF-36), and both the raw and Rasch-based scores of the condition-specific Oxford Knee Score (OKS) in patients undergoing total knee replacement (TKR) METHODS: Data were prospectively collected as part of routine care from adult patients who underwent TKR between 2001 and 2006. OKS data fit the Rasch partial credit model after removing items regarding limping and kneeling. Responsiveness was assessed using effect size (ES), standardised response mean (SRM), and relative validity (RV).

RESULTS

Among 702 patients with complete data at baseline and two follow-ups, the pain subscale of the KS (KS-P), raw-OKS, and Rasch-OKS consistently had higher levels of responsiveness than all eight SF-36 and the other KS subscales. At 6-month follow-up, Rasch-OKS had the largest ES and KS-P had the largest SRM (2.7 and 2.0, respectively). When compared to raw-OKS, the RVs of KS-P, Rasch-OKS, SF-36 bodily pain, and SF-36 physical functioning were 1.1, 0.66, 0.49, and 0.36, respectively. A similar ordering of responsiveness was observed at 24-month follow-up.

CONCLUSION

The OKS and KS-P are more responsive than most SF-36 subscales in TKR patients. Raw-OKS and Rasch-OKS have comparable responsiveness. Different responsiveness indices may give different results.

Knee extension range of motion and self-report physical function in total knee arthroplasty: mediating effects of knee extensor strength

Background

Knee extensor strength and knee extension range of motion (ROM) are important predictors of physical function in patients with a total knee arthroplasty (TKA). However, the relationship between the two knee measures remains unclear. The purpose of this study was to examine whether changes in knee extensor strength mediate the association between changes in knee extension ROM and self-report physical function.

Methods

Data from 441 patients with a TKA were collected preoperatively and 6 months postoperatively. Self-report measure of physical function was assessed by the Short Form 36 (SF-36) questionnaire. Knee extensor strength was measured by handheld dynamometry and knee extension ROM by goniometry. A bootstrapped cross product of coefficients approach was used to evaluate mediation effects.

Results

Mediation analyses, adjusted for clinicodemographic measures, revealed that the association between changes in knee extension ROM and SF-36 physical function was mediated by changes in knee extensor strength.

Conclusions

In patients with TKA, knee extensor strength mediated the influence of knee extension ROM on physical function. These results suggest that interventions to improve the range of knee extension may be useful in improving knee extensor performance.

Evaluation of the relationship between anteroposterior translation of a posterior cruciate ligament-retaining total knee replacement and functional outcome

The success of total knee replacement (TKR) depends on optimal soft-tissue balancing, among many other factors. The objective of this study is to correlate post-operative anteroposterior (AP) translation of a posterior cruciate ligament-retaining TKR with clinical outcome at two years. In total 100 patients were divided into three groups based on their AP translation as measured by the KT-1000 arthrometer. Group 1 patients had AP translation < 5 mm, Group 2 had AP translation from 5 mm to 10 mm, and Group 3 had AP translation > 10 mm. Outcome assessment included range of movement of the knee, the presence of flexion contractures, hyperextension, knee mechanical axes and functional outcome using the Knee Society score, Oxford knee score and the Short-Form 36 questionnaire. At two years, patients in Group 2 reported significantly better Oxford knee scores than the other groups (p = 0.045). A positive correlation between range of movement and AP translation was noted, with patients in group 3 having the greatest range of movement (mean flexion: 117.9° (106° to 130°)) (p < 0.001). However, significantly more patients in Group 3 developed hyperextension > 10° (p = 0.01). In this study, the best outcome for cruciate-ligament retaining TKR was achieved in patients with an AP translation of 5 mm to 10 mm.

An exploratory study of response shift in health-related quality of life and utility assessment among patients with osteoarthritis undergoing total knee replacement surgery in a tertiary hospital in Singapore

OBJECTIVE

To investigate the influence of response shift (RS) on health-related quality of life (HRQOL) and utility assessment among patients undergoing total knee replacement.

METHODS

Consenting patients undergoing total knee replacement were interviewed to determine their HRQOL by using the six-dimensional health state short form, derived from SF-36, and the EuroQol five-dimensional questionnaire at baseline (pretest 1) and the six-dimensional health state short form, derived from SF-36, at 6 (pretest 2) and 18 months after surgery (post-test). RS was studied by using a "then-test" approach by contacting participants 18 months after surgery and asking them to evaluate their HRQOL at baseline (then-test 1) and at 6 (then-test 2) and 18 months after surgery. RS was calculated as the score difference between pretest and then-test scores for a given time point. Relationships between RS and external variables were explored by using univariate and multiple liner regression analyses.

RESULTS

In 74 subjects (63% response rate, median age 68 years), median (interquantile range) six-dimensional health state short form, derived from SF-36, scores for then-tests at baseline (0.48 [0.42-0.49]) and at 6 months (0.72 [0.66-0.79]) after surgery were significantly different from respective pretest scores (0.61 [0.58-0.68] at baseline, P = 0.000; 0.69 [0.63-0.72] at 6 months, P = 0.000), showing RS at both time points. RS at baseline (0.14 [0.08-0.20]) was significantly larger than that at 6 months (-0.05 [0.14 to 0.00], P = 0.000). EuroQol five-dimensional questionnaire pretest and then-test scores at baseline also differed significantly (0.69 [0.17-0.73] vs. -0.18 [-0.23 to 0.00], P = 0.000). RS at baseline was not affected by assessed demographic or medical variables. RS at 6 months was greater in subjects with more years of education (16% of variance in multiple liner regression, P < 0.01).

CONCLUSION

RS was present and impacted HRQOL and utility assessment among patients undergoing total knee replacement before and 6 months after surgery.

Computer-assisted gap balancing technique improves outcome in total knee arthroplasty, compared with conventional measured resection technique

PURPOSE

The objective of this prospective study was to compare the functional outcome of conventional measured resection technique and computer-assisted gap balancing technique in TKA.

METHODS

140 patients were randomized into two groups. The conventional measured resection technique without computer navigation was performed in Group 1 and the computer-assisted gap balancing technique in Group 2. Range of motion, clinical laxity assessment with KT-1000 arthrometer, postoperative radiological films and various functional knee scores were documented at 6 months and 2 years.

RESULTS

At 2 years, there were significantly more patients (five patients, 7%) in the Group 1 with flexion contractures of more than 5° (P = 0.05). There were significantly more outliers in the Group 1 (eight patients, 11%), who demonstrated anterior tibial translation >5 mm, than Group 2 (two patients, 3%) (P = 0.041). The total excursion at 20° was significantly higher in Group 1 at 6 months (P = 0.012) and after 2 years (P = 0.031). Group 2 was able to demonstrate significantly better limb alignment with fewer outliers (more than 3° varus/valgus) than Group 1. At 6-month follow-up, Group 2 demonstrated better outcomes in Function Score (P = 0.040) and Total Oxford Score (P = 0.031). At 2-year review, Group 2 had better outcome in the Total Oxford Score (0.030).

CONCLUSION

Computer-assisted gap balancing technique was able to achieve more precise soft tissue balance and restoration of limb alignment with better knee scores as compared to the conventional measured resection technique in total knee arthroplasty.

Health-related quality of life after total knee replacement or unicompartmental knee arthroplasty in an urban asian population

OBJECTIVE

To examine health-related quality of life (HRQoL) after total knee replacement (TKR) or unicompartmental knee arthroplasty (UKA).

METHODS

Asian adult patients undergoing either TKR or UKA in a hospital in Singapore between 2001 and 2006 were interviewed before surgery and 6 and 24 months postoperatively to obtain demographic information and HRQoL scores using the Short Form-36 Health Survey (SF-36) and the Oxford Knee Score (OKS).

RESULTS

Data were collected from 2243, 1715, and 1113 patients at baseline and at 6 and 24 months, respectively. TKR patients had a lower preoperative OKS than UKA patients and lower preoperative scores on four subscales of the SF-36 (P < 0.01). Both TKR and UKA patients' OKS and SF-36 subscale scores improved 6 months postoperatively except in the general health domain. SF-36 role physical and bodily pain scores showed the most improvement (40.9 and 33.0 points in TKR and 36.9 and 31.4 points in UKA patients, respectively). Two years after surgery, TKR patients' SF-36 scores and OKSs were not significantly different from those of UKA patients except for physical functioning scores. Multiple regression analysis adjusting for demographics showed that baseline scores were a significant predictor of the postoperative OKSs and scores on all SF-36 subscales (P < 0.01), whereas the type of surgery was not associated with the postoperative scores.

CONCLUSIONS

Both TKR and UKA patients experienced significant improvements in HRQoL, particularly in the role physical and pain domains. After controlling for potential confounding variables, the type of surgery was not a significant predictor of patients' postoperative HRQoL scores.

Single-dose periarticular steroid infiltration for pain management in total knee arthroplasty: a prospective, double-blind, randomised controlled trial

INTRODUCTION

Post total knee replacement pain control using parenteral opioids results in significant side effects like nausea and vomiting. Periarticular injections are used to control pain without these side effects. This study aimed to evaluate the safety and efficacy of periarticular steroid injection in patients undergoing total knee arthroplasty, as well as assess the patient's functional outcomes over a period of two years.

METHODS

A total of 100 patients who underwent total knee arthroplasty were randomised into two groups. The treatment group received periarticular infiltration with triamcinolone acetonide, bupivacaine and epinephrine. The control group received only bupivacaine and epinephrine. The postoperative analgesic regime was standardised for all patients. The immediate postoperative outcomes evaluated included pain score, morphine consumption, time to ambulation, straight leg raise, range of motion and duration of hospital stay. Longer-term outcomes were assessed at 1, 3, 6 and 24 months using the SF-36 questionnaire and Oxford Knee Score.

RESULTS

Patients in the treatment group had significantly lower pain scores, reduced morphine consumption and earlier discharge. They also had better range of knee motion and were able to regain muscular strength earlier. There was no increase in major complications such as infection or tendon rupture in the treatment group. There was no difference between the groups with regard to the medium-term outcomes of up to two years.

CONCLUSION

This modality of pain control is safe and efficacious for post total knee replacement pain control.

Use of a disease-specific instrument in economic evaluations: mapping WOMAC onto the EQ-5D utility index

OBJECTIVE

To map the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) onto the EuroQol 5 Dimension (EQ-5D) utility index in patients with knee osteoarthritis (OA).

METHODS

A consecutive sample of patients (n=258) diagnosed with knee OA completed both the WOMAC and the EQ-5D. Regression models with the ordinary least squares (OLS) or the censored least absolute deviations as the estimator were used to establish the mapping function. The WOMAC was represented as explanatory variables in four ways: 1) total score; 2) domain scores (i.e., pain, stiffness, and physical function); 3) domain scores plus pair-wise interaction terms to account for possible nonlinearities; and 4) individual item scores. Goodness-of-fit criteria included the mean absolute error (the primary criterion) and the root mean squared error, and were obtained using an iterative random sampling procedure. Prediction precision was evaluated at individual patient level and at the group level.

RESULTS

The model using the OLS estimator and the WOMAC domain scores as explanatory variables had the best fit and was chosen as the preferred mapping model. The prediction error at the individual level exceeded the maximal tolerance value (i.e., the minimally important difference of the EQ-5D) in about 16% of the patients. At the group level, the width of the 95% confidence interval of prediction errors varied from 0.0176 at a sample size of 400 to 0.0359 at a sample size of 100.

CONCLUSIONS

EQ-5D scores can be predicted using WOMAC domain scores with an acceptable precision at both individual and group levels in patients with mild to moderate knee OA.

Evaluation of health outcomes in osteoarthritis patients after total knee replacement: a two-year follow-up

Objectives

To quantify the improvement in health outcomes in patients after total knee replacement (TKR).

Methods

This was a two-year non-randomized prospective observational study in knee osteoarthritis (OA) patients undergone TKR. Patients were interviewed one week before, six months after, and two years after surgery using a standardized questionnaire including the SF-36, the Oxford Knee Score (OKS), and the Knee Society Clinical Rating Scale (KSS). A generalized estimating equation (GEE) model was used to estimate the magnitudes of the changes with and without the adjustment of age, ethnicity, BMI, and years with OA.

Results

A total of 298 (at baseline), 176 (at six-months), and 111 (at two-years) eligible patients were included in the analyses. All the scores changed significantly over time, with the exception of SF-36 social functioning, vitality, and mental health. With the adjustment of covariates, the magnitude of changes in these scores was similar to those without the adjustment.

Conclusions

Both general and knee-specific physical functioning had been significantly improved after TKR, while other health domains have not been substantially improved after the surgery.

Total or partial knee replacement? Cost-utility analysis in patients with knee osteoarthritis based on a 2-year observational study

The objective of this study was to evaluate incremental cost-utility of total knee replacement (TKR) versus unicompartmental knee arthroplasty (UKA) in patients with knee osteoarthritis (OA) of the medial compartment. A 2-year non-randomised prospective observational cohort study was conducted in unicompartmental knee osteoarthritis patients scheduled for TKR (n = 431) or UKA (n = 102). Costs were identified using administrative databases and health outcomes were measured using the SF-36 and the Oxford knee score (OKS) 1 week before, 6 months after, and 2 years after surgery. The incremental cost-utility ratio (ICUR) for TKR versus UKA was calculated and its 95% confidence interval estimated using a nonparametric bootstrapping technique. Cost-effectiveness acceptability curves were constructed from different perspectives. On average, from the societal perspective, the ICUR was US $65,245 per quality-adjusted life-year (QALY). In the scenario with costs calculated from the perspective of patients, the ICUR was $60,382/QALY. This value decreased to $4,860/QALY in the scenario with costs calculated from the governmental perspective. However, the 95% confidence interval of ICURs cannot be defined because more than 5% bootstrapped samples fell into the upper left quadrant of the cost-effectiveness plane from all three perspectives. Based on the 2-year data, TKR gained more QALYs at higher costs compared to UKA. A long-term prospective study is necessary to determine cost-effectiveness of TKR and UKA.

Thromboembolic prophylaxis for total knee arthroplasty in Asian patients: a randomised controlled trial

PURPOSE

To compare the efficacy and safety of different modes of thromboembolic prophylaxis for elective total knee arthroplasty (TKA) in Asian patients.

METHODS

440 low-risk patients undergoing TKA were randomised into 4 equal groups: (1) no prophylaxis (control), (2) graduated compression stockings (GCS), (3) intermittent pneumatic compression (IPC), and (4) low-molecular-weight heparin (enoxaparin). Duplex ultrasonography was used as an assessment tool.

RESULTS

The deep vein thrombosis point prevalence was highest in the control group (22%), which was significantly higher than in patients receiving IPC (8%, p=0.032) or enoxaparin (6%, p=0.001). One patient each in the control and GCS groups developed a non-fatal pulmonary embolism. Patients on enoxaparin received more blood transfusions and 2 of them had major bleeding complications.

CONCLUSION

IPC is the preferred method of thromboprophylaxis for TKA in Asian patients.

Does computer-assisted surgical navigation total knee arthroplasty reduce venous thromboembolism compared with conventional total knee arthroplasty?

INTRODUCTION

The study aims to show that total knee arthroplasty using computer-assisted surgical navigation without intramedullary rodding is safer than conventional intramedullary techniques in preventing venous thromboembolism.

METHODS

30 patients were grouped into groups of 10. Groups A and B had conventional intramedullary rodding of the femur and/or tibia. Group C had no rodding of the femur and tibia using computer-assisted surgical navigation. The degree, duration and size of the embolic shower were captured by a transoesophageal echocardiography probe. The echogenic emboli were graded according to the Mayo Clinic score. Haemodynamic parameters such as pulse oximetry oxygen saturation, end-tidal carbon dioxide, heart rate and mean arterial pressure were also recorded.

RESULTS

There was a significant difference in the size of the emboli and the Mayo Clinic score when comparing the groups with intramedullary rodding and those without. There was also a significant difference in the pulse oximetry oxygen saturation and heart rate when the group without intramedullary rodding was compared with groups with rodding.

CONCLUSION

Surgical navigation total knee arthroplasty may be safer than conventional total knee replacement with intramedullary rodding in preventing venous thromboembolism.

A study on indirect and intangible costs for patients with knee osteoarthritis in Singapore

OBJECTIVES

To estimate indirect costs through human capital approach and intangible costs through willingness-to-pay (WTP), and identify factors potentially affecting these costs in multiethnic Asian patients with knee osteoarthritis (OA).

METHODS

Data were collected through face-to-face interviews among knee OA patients. Human capital approach was used to estimate indirect costs by multiplying: 1) days of absence from work because of OA, with average earnings per capita per day for working patients; or 2) productivity loss with the market price of housekeeping for retirees/homemakers. A closed-ended iterative bidding contingent valuation method was used to elicit willingness-to-pay for a hypothetical cure of OA as a proxy for intangible costs. Mann-Whitney U or Kruskal-Wallis H-tests were performed in univariate analyzes, and linear regression in multivariate analyses.

RESULTS

Indirect costs per year and intangible costs were estimated at US$1008 and US$1200, accounting for 2.8% and 3.3% of annual household income, respectively. The indirect costs were significantly higher for male or working patients, while intangible costs were higher for Chinese, working patients, with higher income, or worse global well-being.

CONCLUSION

This study demonstrated that eliciting indirect costs through human capital approach and intangible costs through WTP are acceptable and feasible in Asian patients with knee OA. Besides the direct costs, the indirect and intangible costs for the OA patients could be substantial.

Computer-assisted minimally invasive total knee arthroplasty compared with standard total knee arthroplasty. A prospective, randomized study

BACKGROUND

There is little information on the feasibility of computer navigation when using a minimally invasive approach for total knee arthroplasty, during which the anatomic landmarks for registration may be obscured. The purpose of the present study was to determine the radiographic accuracy of this technique and to compare the rate of functional recovery between patients who underwent computer-assisted minimally invasive arthroplasty and those who underwent conventional total knee arthroplasty.

METHODS

One hundred and eight consecutive patients were randomized to undergo computer-assisted minimally invasive total knee arthroplasty or conventional total knee arthroplasty. Perioperative pain management was standardized. The clinical parameters, long-leg radiographs, and functional assessment scores were evaluated for six months postoperatively.

RESULTS

Patients who underwent computer-assisted minimally invasive total knee arthroplasty had a significantly longer operative time (by a mean of twenty-four minutes) and a significantly shorter inpatient stay (3.3 compared with 4.5 days) in comparison with those who underwent conventional arthroplasty (p </= 0.001). Significantly more patients in the computer-assisted minimally invasive total knee arthroplasty group were able to walk independently for more than thirty minutes at one month (p = 0.04). The percentage of patients with a coronal tibiofemoral angle within +/-3 degrees of the ideal was 92% for the computer-assisted minimally invasive total knee arthroplasty group, compared with 68% for the conventional total knee arthroplasty group (p = 0.003).

CONCLUSIONS

Although specific clinical parameters reflect an early increased rate of functional recovery in association with computer-assisted minimally invasive total knee arthroplasty within the first postoperative month, the main advantage of this technique over conventional total knee arthroplasty is improved postoperative radiographic alignment without increased short-term complications.